2. Introduction to Ideotype breeding
• In broad sense an Ideotype is a “biological model
which is expected to perform or behave in a
predictable manner within a defined
environment.”
• More specifically, crop Ideotype is a plant model
which is expected to yield greater quantity of
grains, fiber, oil or other useful product when
developed as a cultivar.
• The term Ideotype was first proposed by Donald
in 1968 working on wheat
3. MAIN POINT OF IDEOTYPE
1. Crop Ideotype refers to model plants for
specific environment.
2. Ideotype differs from Idiotype.
3. It include morphological as well as
physiological and biochemical traits.
4. Ideotype is a moving goal.
5. It is difficult and slow method of cultivar
development
4. STEPS IN IDEOTYPE BREEDING
1) Development of conceptual theoretical
model.
2) Selection of base material.
3) Incorporation of desirable characters into
single genotype.
4) Selection of ideal or model plant type.
5. DEVELOPMENT OF CONCEPTUAL
THEORETICAL MODEL
1. Ideotype consists of various morphological and
physiological traits. The values of various
morphological and physiological traits are specified to
develop a conceptual theoretical model.
2. For example,
Plant height is important in fodder crops.
Maturity duration is important in rainfed.
Similarly leaf number, leaf angle, leaf size,
photosynthetic rate,etc are specified for each crops
and situation
6. SELECTION OF BASE MATERIAL
1. Selection of base material is an important step after
development of conceptual model of Ideotype.
2. Genotype to be used in devising a model plant type
should have broad genetic base and wider adaptability so
that the new plant type can be successfully grown over a
wide range of environmental condition with stable yield.
3. Genotypes for plant stature, maturity duration, leaf size,
and angles are selected from the global gene pool of the
concerned crop species.
4. Genotypes resistant or tolerant to drought, soil salinity,
alkalinity, disease and insects are selected from the gene
pool with the cooperation of physiologist, soil scientist,
pathologist and entomologist.
7. INCORPORATION OF DESIRABLE
TRAITS
1. The next important step is combining of various
morphological and physiological traits from different
selected genotypes into single genotype.
2. Knowledge of the association between various characters
is essential before starting hybridization programme,
because it help in combining of various characters.
3. Linkage between procedures, viz single cross, three way
cross, multiple cross, backcross, composite crossing. E.g.
Mutation breeding, heterosis breeding, etc. are used for
the development of ideal plant types in majority of field
crops. Backcross technique is commonly used for transfer
of oligogenic traits from selected germplasm lines into the
background of an adapted genotype.
8. SELECTION OF IDEAL PLANT TYPE
1. Plant combining desirable morphological and physiological traits
are selected in segregating population and intermated to achieve
the desired plant type.
2. Morphological features are judged through visual observation
and physiological parameters are recorded with the help of
sophisticated instruments.
3. Screening for resistance to drought, soil salinity, alkalinity, disease
and insects is done under controlled conditions. This task is
completed with the help of scientist from the disciplines of
physiology, soil science, pathology and entomology.
4. Finally, genotypes combining traits specified in the conceptual
model are selected, multiplied, tested over several locations, and
released for commercial cultivation
9. MERITS OF IDEOTYPE BREEDING
1. Ideotype breeding is an effective method of breaking
yield barriers through the use of genetically controlled
physiological variation for various characters
contributing towards higher yield.
2. Ideotype breeding provides solution to several
problems at a time like disease, insect and lodging
resistance, maturity duration, yield and quality by
combining desirable genes for these traits from
different sources into a single genotype.
3. It is efficient method of developing cultivars for
specific or environment
10. DEMERITS OF IDEOTYPE BREEDING
1. Incorporation of several desirable morphological and
physiological and disease resistance traits from
different sources into a single genotype is a difficult
task. Sometimes, combining of some characters is not
possible due to tight linkage between desirable and
undesirable characters. Presence of such linkage
hinders the progress of Ideotype breeding.
2. Ideotype breeding is a slow method of cultivar
development, because combining together of various
morphological and physiological features from
different sources takes more time than traditional
breeding where improvement is made in yield and
one or two other characters
